Aqueous ink compositions

ABSTRACT

1. An ink comprising water, a water-dissipatable polymer and a dye, wherein the dye carries a group of the Formula (1):wherein:R1 is optionally substituted branched chain alkyl; andR2 is H, optionally substituted alkyl or optionally substituted aryl.The inks are useful in ink jet printers.

This invention relates to inks and to their use in ink jet printing.

Ink jet printing methods involve printing an image onto a substrateusing ink droplets emitted from a small nozzle without bringing thenozzle into contact with the substrate. Over recent years ink jetprinters have become popular because they are quieter and more versatilethan impact printers, for example conventional basket typewriters arenoisy and the images they can print are restricted to the shapes mouldedonto the end of each mechanical lever. The most popular ink jet printersare the thermal and piezoelectric.

The requirements for inks used in ink jet printers include:

i) they should not clog the small nozzle from which they are emitted, orform a blocking crust over the end,

ii) the resultant image should have good water-fastness so that it doesnot smudge excessively on contact with sweat or water,

iii) the image should also have a good light-fastness so that it doesnot fade quickly on exposure to daylight,

iv) they should dry quickly on paper and give discrete, sharp images,

v) they should have good storage stability, and

vi) they should have a high colour strength to give intensly colouredimages.

We have now found that very good ink jet printing inks may be preparedhaving the compositions defined below.

According to the present invention there is provided an ink comprisingwater, a water-dissipatable polymer and a dye, wherein the dye carries agroup of the Formula (1):

wherein:

R¹ is optionally substituted branched chain alkyl; and

R² is H, optionally substituted alkyl or optionally substituted aryl.

Preferably R¹ is α-branched optionally substituted alkyl, morepreferably a group of the formula —CHR³R⁴ wherein R³ and R⁴ are eachindependently optionally substituted alkyl or R³ and R⁴ together withthe CH group to which they are attached from an optionally substituted5- or 6- membered ring. Preferably R¹ has from 3 to 20 carbon atoms,more preferably 3 to 10 carbon atoms. Examples of preferred groupsrepresented by R¹ include prop-2-yl, but-2-yl, pent-2-yl, pent-3-yl,hex-2-yl, hex-3-yl, hept-2-yl, cyclopentyl and cyclohexyl.

When the group —CHR³R⁴ forms a 5- or 6-membered ring the ring ispreferably a cyclohexyl or cyclopentyl ring.

R² is preferably optionally substituted aryl, more preferably optionallysubstituted alkyl.

When R² is optionally substituted aryl it is preferably an optionallysubstituted phenyl.

When R² is an optionally substituted alkyl group it can be straightchain or branched chain. Preferably R² is C₁₋₂₀-alkyl, more preferablyC₁₋₁₀-alkyl, especially C₁₋₆-alkyl, more especially C₂-C₆-alkyl, each ofwhich is optionally substituted.

The optional substituents which may be present on R¹, R², R³ and R⁴ arepreferably selected from C₁₋₄-alkoxy, especially methoxy; halo,especially Cl, Br or F; C₁₋₄-alkyl, especially methyl; nitro; cyano;optionally substituted amino, especially —NR^(a)R^(b) wherein R^(a) andR^(b) are each independently H, C₁₋₄-alkyl or C₁₋₄-alkyl substituted byhydroxy, carboxy or sulpho; or an ester group, especially —OCOR^(a) or—CO₂R^(a) wherein R^(a) is as hereinbefore defined.

In a preferred embodiment the group of Formula (1) is attached to aphenyl group in the dye, more preferably to a phenyl group carrying anazo, imine or alkylene substituent, especially such a substituent at the4-position relative to the group of Formula (1).

In preferred ink the group of Formula (1) is attached to a phenyl groupcarrying an azo substituent at the 4-postion, more preferably the dye isof the Formula:

wherein:

A is the residue of a diazotisable aromatic or heterocyclic amine;

B is an optionally substituted 1,4-phenylene group; and R¹ and R² are ashereinbefore defined.

A is preferably phenyl, naphthyl, thaizolyl, isothiazolyl,benzothiazolyl, benzoisothiazolyl, pyrazolyl, thiadiazolyl, triazolyl,imidazolyl, thienyl, pyridyl or pyridoisothiazolyl, each of which isoptionally substituted.

When A is phenyl it is preferably of the Formula (2):

wherein:

R⁵ is —H, optionally substituted alkyl, optionally substituted alkoxy,—NO₂, —CN, —CHO, alkenyl, —CF₃, —SCN, halogen, acyl, ester, amide,thioalkyl or thioaryl, —SO₂NH₂, —SO₂F, —SO₂Cl, —CONH₂, —COF or —COCl;and

n is an integer from 1 to 5.

When R⁵ is acyl it is preferably —CO(C₁₋₄-alkyl), —SO(C₁₋₄-alkyl) or—SO₂(C₁₋₄-alkyl); when R⁵ is an ester it is preferably —OCO(C₁₋₄-alkyl),—COO(C₁₋₄-alkyl) or —SO₃ (C₁₋₄-alkyl); when R⁵ is amide it is preferablya carbonamido or sulphonamido group, more preferably—CONH(C₄-alkyl),—NHCO(C₁₋₃-alkyl), —CON(C₁₋₄-alkyl)₂, —SO₂NH(C₁₋₄-alkyl),—NHSO₂(C₁₋₄-alkyl) or —SO₂N (C₁₋₄-alkyl)₂; when R⁵ is thioalkyl orthioaryl it is preferably —S(C₁₋₄-alkyl) or —S(phenyl).

When A is naphthyl it is preferably of the Formula (3):

wherein:

R⁵ is as hereinbefore defined; and

n¹ is an integer from 1 to 4.

When A is thiazolyl it is preferably of the Formula (4):

wherein:

R⁶ is —H, optionally substituted alkyl, optionally substituted alkoxy,optionally substituted aryl, halogen or —Salkyl; and

R⁷ is —H, optionally substituted alkyl, alkenyl, —CN, —NO₂, —SO₂alkyl,—COOalkyl, halogen or —CHO.

When A is isothiazolyl it is preferably of the Formula (5):

wherein:

R⁸ is —H, optionally substituted alkyl, optionally substituted aryl,optionally substituted pyridyl, —SO₂alkyl, —Salkyl, —Saryl or halogen;and

R⁹ is —H, —CN, —NO₂, —SCN or —COOalkyl.

When A is benzothiazolyl it is preferably of the Formula (6):

wherein:

R¹⁰ is —H, —SCN, —NO₂, —CN, halogen, optionally substituted alkyl,optionally substituted alkoxy, —COOalkyl, —OCOalkyl or —SO₂alkyl; and

n² is from 1 to 4.

When A is benzoisothiazolyl it is preferably of the Formula (7):

wherein:

R¹⁰ as hereinbefore defined; and

n³ is from 1 to 4.

When A is pyrazolyl it is preferably of the Formula (8):

wherein:

each R⁷ independently is as hereinbefore defined; and

R¹¹ is —H, optionally substituted alkyl or optionally substituted aryl,

When A is thiadiazolyl or triazolyl it is preferably of Formula (9) or(10):

wherein:

R¹² is —Salkyl, —Saryl, —SO₂alkyl, halogen or optionally substitutedC₁₋₄-alkyl; and

W is S or N.

When A is imidazolyl it is preferably of the Formula (11):

wherein:

R¹³ is —CN, —CHO, —CH═C(CN)₂ or —CH═C(CN)(COOalkyl);

R¹⁴ is —CN or —Cl; and

R¹⁵ is —H or optionally substituted alkyl.

When A is thienyl it is preferably of the Formula (12):

wherein:

R¹⁶ is —NO₂, —CN, alkylcarbonylamino or alkoxycarbonyl;

R¹⁷ is —H, halogen, optionally substituted alkyl, optionally substitutedalkoxy, optionally substituted aryl or —Salkyl; and

R¹⁸ is —H, optionally substituted alkyl, —CN, —NO₂, —SO₂alkyl,—COOalkyl, halogen, —CH═C(CN)₂ or —CH═C(CN)(COOalkyl).

When A is pyridyl it is preferably of the Formula (13):

wherein:

R⁵ is as hereinbefore; and

n⁴ is from 1 to 4.

When A is pyridoisothaizolyl it is preferably of the Formula (14):

wherein:

R¹⁹ is —CN or —NO₂; and

R²⁰ is optionally substituted alkyl.

When any of R² to R²⁰ is optionally substituted alkyl, optionallysubstituted alkoxy or optionally substituted aryl the optionalsubstituents are preferably selected from —CN, —SCN, —NO₂, halogen,especially —F, —Cl and —Br, —SC₁₋₄-alkyl, —Sphenyl, C₁₋₄-alkoxy and—COOC₁₋₄-alkyl.

When any of R³ to R²⁰ is or contains an alkyl or alkoxy group it ispreferably C₁₋₆-alkyl or C₁₋₆-alkoxy, more preferably C₁₋₄-alkyl, orC₁₋₄-alkoxy.

The halogen group represented by R⁵, R⁶, R⁷, R⁸, R¹⁰, R¹² or R¹⁸ ispreferably —F, —Cl or —Br.

Especially preferred groups represented by R⁵ are selected from —NO₂,—CN, —COOC₁₋₄-alkyl and C₁₋₄-alkyl.

In phenyl groups of Formula (2) n is preferably from 1 to 3, morepreferably 1 or 2. When the phenyl group of Formula (2) carries 3substituents these are preferably in the 2-, 4- and 6-positions. Whenthe phenyl group of Formula (3) carries 1 or 2 substituents these arepreferably in the 2- or 4- or in both the 2- and 4- positions, morepreferably in the 4-position with respect to the —N═N— linkage.

The optionally substituted aryl group represented by R⁶, R⁸, R¹¹ or R¹⁷is preferably phenyl or substituted phenyl.

R⁶ is preferably —H, optionally substituted C₁₋₄-alkyl, optionallysubstituted C₁₋₄-alkoxy, optionally substituted phenyl, —F, —Cl, —Br or—SC₁₋₄-alkyl, more preferably —H, C₁₋₄-alkyl, C₁₋₄-alkoxy, phenyl or—SC₁₋₄-alkyl and especially —H, —CH₃ or C₂H₅.

R⁷ is preferably —H, optionally substituted C₁₋₄-alkyl , —CN, —NO₂,—SO₂C₁₋₄-alkyl, —COOC₁₋₄-alkyl, —Cl, —F, Br or —CHO, C₂₋₆-alkenyl, morepreferably —H, C₁₋₄-alkyl, cyano-C₁₋₄-alkyl, —CN, —NO₂, —CHO,C₂₋₃-alkenyl and especially —NO₂, —CN, —CHO, vinyl or —CH₂CN.

R⁸ is preferably —H, optionally substituted C₁₋₄-alkyl, optionallysubstituted phenyl, —SO₂C₁₋₄-alkyl, —SC₁₋₄-alkyl, —Sphenyl, —Cl, —F or—Br, more preferably C₁₋₄-alkyl, phenyl or —SO₂C₁₋₄-alkyl, andespecially —CH₃ or —CO₂CH₃.

R⁹ is preferably —CN, —NO₂, —SCN or —COOC₁₋₄-alkyl, more preferably —CNor —NO₂.

In benzothiazolyl groups of Formula (6) n² is preferably 1 or 2, morepreferably 1. The substituent represented by R¹⁰ is preferably in the6-position.

R¹⁰ is preferably —H, —SCN, —NO₂, —Cl, —F, Br, optionally substitutedC₁₋₄-alkyl, optionally substituted C₁₋₄-alkoxy, —COOC₁₋₄-alkyl,—OCOC₁₋₄-alkyl or —SO₂C₁₋₄-alkyl, more preferably —H, —SCN, —NO₂,C₁₋₄-alkoxy or —SO₂C₁₋₄-alkyl and especially —SCN or —SO₂CH₃.

In benzoisothiazolyl groups of Formula (7) n³ is preferably 1 or 2, morepreferably 1.

R¹¹ is preferably —H, optionally substituted C₁₋₄-alkyl or optionallysubstituted phenyl, more preferably cyano-C₁₋₄-alkyl and, especiallycyanomethyl.

R¹² is preferably —SC₁₋₄-alkyl, —Sphenyl or —SO₂C₁₋₄-alkyl, morepreferably —SC₁₋₄-alkyl and —SO₂C₁₋₄-alkyl, especially —SCH₃ or —SC₂H₅.

R¹³ is preferably —CN, —CHO, —CH═C(CN)₂ or —CH═C(CN)COOC₁₋₄-alkyl andmore preferably —CN.

R¹⁴ is preferably —CN.

R¹⁵ is preferably cyano-C₁₋₄-alkyl, especially cyanomethyl.

R¹⁶ is preferably —NO₂, —CN, C₁₋₄-alkylcarbonylamino orC₁₋₄-alkoxycarbonyl more preferably —NO₂, —CN, ethoxycarbonyl ormethylaminocarbonyl.

R¹⁷ is preferably —H, halogen, optionally substituted C₁₋₄-alkyl,optionally substituted C₁₋₄-alkoxy, optionally substituted phenyl—SC₁₋₄-alkyl, more preferably C₁₋₄-alkoxy, —Cl, —Br, phenyl,—SC₁₋₄-alkyl and especially —H, —Cl or methyl.

R¹⁸ is preferably —H, C₁₋₄-alkyl, —CN, —NO₂, —SO₂C₁₋₄-alkyl,—COOC₁₋₄-alkyl, —Cl, —F, —Br, —CH═C(CN)₂ or —CH═C(CN)(COOC₁₋₄-alkyl) andmore preferably —NO₂, —CN, —CH═C(CN)₂ or —CH═C(CN)(COOC₁₋₄-alkyl).

In pyridyl groups of Formula (13) n⁴ is preferably from 1 to 3, morepreferably 1 or 2 and especially 1.

When B is substituted it is preferred that the substituent(s) are in oneor more of the 2-,3-,5- and 6-positions, more preferably in one or moreof the 2- and 3-positions, especially in the 3-position with respect tothe -NR¹R² group.

In a preferred sub-group of inks the group A is phenyl, isothiazol-5-yl,benzoisothiazol-3-yl, 1,2,4-thiadiazol-5-yl, 1,3,4-thiadiazol-5-yl orpyrazol-5-yl; B is 1,4-phenylene which is unsubstituted or carries a3-methyl or a 3-acetylamino substituent; R¹ is an α-branched optionallysubstituted C₃₋₁₀-alkyl group; and R² is C₁₋₁₀-alkyl.

In a further preferred sub-group of inks A is phenyl, thiazol-2-yl,isothiazol-5-yl, 1,3,4-thiadiazol-5-yl or thien-2-yl; B is 1,4-phenylenewhich is unsubstituted or carries a 3-methyl or a 3-acetylaminosubstituent; R¹ is an α-branched optionally substituted C₃₋₁₀-alkylgroup; and R² is C₁₋₁₀-alkyl.

In a further preferred sub-group of inks R¹ is sec-butyl, isopropyl orα-methylbenzyl; R² is ethyl, n-butyl, 2-phenoxyethyl, 2-acetoxyethyl orsec-butyl; B is 1,4-phenylene which is unsubstituted or carries a3-methyl or a 3-acetylamino substituent; and A is3-methyl-4-cyanoisothiazol-5-yl, benzoisothiazol-3-yl,1,2,4-thiadiazol-5-yl or 1,3,4-thiadiazol-5-yl or pyrazol-5-yl.

In a further preferred sub-group of inks R¹ is sec-butyl, isopropyl orα-methylbenzyl; R² is ethyl, n-butyl, 2-acetoxyethyl or sec-butyl; B is1,4-phenylene which is unsubstituted or carries a 3-methyl or3-acetylamino substituent; and A is 3-methyl-4-cyanoisothiazol-5-yl.

In a further preferred sub-group of inks R¹ is sec-butyl, isopropyl orα-methylbenzyl; R² is ethyl, n-butyl, 2-phenoxyethyl, 2-acetoxyethyl orsec-butyl; B is 1,4-phenylene which carries a 3-methyl or 3-acetylaminosubstituent; and A is 3-methyl-4-cyanoisothiazol-5-yl.

In a further preferred sub-group of inks R¹ is sec-butyl, orα-methylbenzyl; R² is ethyl, n-butyl, 2-phenoxyethyl, 2-acetoxyethyl orsec-butyl; B is 1,4-phenylene which carries a 3-acetylamino substituent;and A is 4-cyano-3-methylisothiazol-5-yl.

As mentioned above, in a preferred class of inks the dye carries a groupof Formula (1) attached to a 1,4-phenylene group carrying an imine oralkylene substituent at the 4-position. In inks of this class the dye ispreferably of the formula:

wherein:

X¹ is N or C;

a is 0 when X¹ is N;

a is 1 when X¹ is C;

R¹⁹ is —H, —CN or —COOalkyl;

R¹, R² and B are as hereinbefore defined; and

Y¹ is a homocyclic ring, a heterocyclic ring, a carbon atom carrying anelectron withdrawing group or Y¹ together with X¹ and (R¹⁹)a forms ahomocyclic or heterocyclic ring.

R¹⁹ is preferably —H, —CN or —CO₂(C₁₋₄-alkyl), more preferably —H or—CN, especially —CN.

When Y¹ is a homocyclic ring it is preferably of the Formula (15):

wherein:

K and L are each independently H, alkyl, amido or halo; or

K and L together with the carbon atom to which they are attached form a5- or 6- membered ring, preferably a 5- or 6- membered heterocyclic orcarbocyclic ring.

When K or L is alkyl it is preferably C₁₋₄-alkyl. When K or L is amidoit is preferably —NHCOC₁₋₄-alkyl, —CONHC₁₋₄-alkyl, —NHCOaryl or—CONHaryl; the aryl group is preferably phenyl. When K or L is halo itis preferably F, Cl or Br.

When Y¹ together with X¹ and (R¹⁹) a forms a heterocyclic ring theypreferably form a ring of the formula:

wherein R¹⁵ is as hereinbefore defined.

When Y₁ is a heterocyclic ring it is preferably of the Formula (16),(17) or (18):

wherein:

Ph is phenyl;

X, Y and Z are each independently N or C—R²¹; each

R²⁰ independently is an electron withdrawing group; and

R²¹ is H, CN, alkyl, alkoxy, cycloalkyl, aryl, aralkyl, aryloxy oramino.

When Y¹ is a carbon atom carrying an electron withdrawing group it ispreferably of the Formula (19):

wherein:

R²⁰ is as hereinbefore defined; and

R²¹ is H, C₁₋₄-alkyl or an electron withdrawing group.

R²⁰ is preferably —CN, —NO₂, —CO(C₁₋₄-alkyl) or —COO(C₁₋₄-alkyl).

R²¹ is.preferably H, —CN, —C₁₋₄-alkyl, phenyl or a group of Formula(20):

In Formulae (15) to (19) the carbon atom marked with an asterisk (*) isthe point of attachment to the double bond which is itself attached toX¹.

Dyes carrying a group of Formula (1) may be prepared in an analogousmanner to known dyes, except that an intermediate is chosen whichcarries a group of Formula (1). For example, the first class of dyerepresented by the formula A—N═N—B—NR¹R² may be prepared by diazotisingan amine of formula A—NH₂, preferably below 5° C. in dilute mineral acidusing NaNO₂, and coupling to a compound of formula H—B—NR¹R², wherein A,B, R¹ and R² are as hereinbefore defined. Numerous texts describegeneral methods for synthesising dyes, including Organic Chemistry inColour, P. F. Gordon and P. Gregory, (ISBN 3-540-17260-2), chapter 2.4entitled ‘Synthesis of Dyes’ and The Chemistry of Synthetic Dyes,Volumes I to VII, K. Venkataraman, and The Chemistry and Application ofDyes, G. Hallas and D. R. Waring ISBN 0-306-43278-1.

The water-dissipatable polymer preferably bears ionised carboxy and/orsulphonate groups, especially ionised sulphonate groups, because theseassist water dissipatability of the polymer. Such groups can be chainpendant and/or terminal.

The water-dissipatable polymer is preferably a water-dissipatablepolyester. The water-dissipatable polyester can be prepared usingconventional polymerisation procedures known to be effective forpolyester synthesis. Thus, it is well known that polyesters containcarbonyloxy (i.e —C(═O)—O—) linking groups and may be prepared by acondensation polymerisation process in which an acid component(including ester-forming derivatives thereof) is reacted with a hydroxylcomponent. The acid component may be selected from one or more polybasiccarboxylic acids, e.g. di- and tri-carboxylic acids or ester-formingderivatives thereof, for example acid halides, anhydrides or esters. Thehydroxyl component may be one or more polyhydric alcohols or phenols(polyols), for example, diols, triols, etc. (It is to be understood,however, that the polyester may contain, if desired, a proportion ofcarbonylamino linking groups —C(═O)—NH— (i.e. amide linking groups) byincluding an appropriate amino functional reactant as part of the“hydroxyl component”; such as amide linkages). The reaction to form apolyester may be conducted in one or more stages. It is also possible tointroduce in-chain unsaturation into the polyester by, for example,employing as part of the acid component an olefinically unsaturateddicarboxylic acid or anhydride.

Polyesters bearing ionised sulphonate groups may be prepared by using atleast one monomer having two or more functional groups which willreadily undergo an ester condensation reaction (e.g carboxyl groups,hydroxyl groups or esterifiable derivatives thereof) and one or moresulphonic acid groups (for subsequent neutralisation after polyesterformation) or ionised sulphonate groups (i.e. neutralisation of thesulphonic acid groups already having been effected in the monomer) inthe synthesis of the polyester. In some cases it is not necessary toneutralise sulphonic acid groups since they may be sufficiently strongacid groups as to be considerably ionised in water even without theaddition of base. Often, the sulphonic acid or ionised sulphonatecontaining monomer is a dicarboxylic acid monomer having at least oneionised sulphonate substituent (thereby avoiding any need to effectneutralisation subsequent to polyester formation). (Alternatively, alkylcarboxylic acid ester groups may be used in place of the carboxylic acidgroups as ester-forming groups). Such a monomer will therefore be partof the acid component used in the polyester synthesis.

Preferred polybasic carboxylic acids which can be used to form thepolyester have two or three carboxylic acid groups. For example, one canuse C₄ to C₂₀ aliphatic, alicyclic and aromatic compounds having two ormore carboxy groups and their ester forming derivatives (e.g. esters,anhydrides and acid chlorides), and dimer acids such as C36 dimer acids.Specific examples include adipic acid, fumaric acid, maleic acid,succinic acid, itaconic acid, sebacic acid, nonanedioic acid,decanedioic acid, 1,4-cyclohexanedicarboxylic acid,1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid,terephthalic acid, isophthalic acid, phthalic acid andtetrahydrophthalic acid and their acid chlorides. Anhydrides includesuccinic, maleic, phthalic and hexahydrophthalic anhydrides.

Preferred polyols which can be used to form the polyester include thosehaving from 2 to 6, more preferably 2 to 4 and especially 2 hydroxylgroups per molecule. Suitable polyols having two hydroxy groups permolecule include diols such as 1,2-ethanediol, 1,3-propanediol,1,4-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3- propanediol (neopentylglycol), the 1,2-, 1,3- and 1,4-cyclohexanediols and the correspondingcyclohexane dimethanols, diethylene glycol, dipropylene glycol, anddiols such as alkoxylated bisphenol A products, e.g. ethoxylated orpropoxylated bisphenol A. Suitable polyols having three hydroxy groupsper molecule include triols such as trimethylolpropane (1,1,1-tris(hydroxymethyl)ethane). Suitable polyols having four or more hydroxygroups per molecule include pentaerythritol(2,2-bis(hydroxymethyl)-1,3-propanediol) and sorbitol(1,2,3,4,5,6-hexahydroxyhexane).

Compounds having two or more groups which readily undergo an estercondensation reaction and have one or more sulphonate groups aredicarboxylic acid monomers having at least one ionised sulphonate group.Examples of such compounds are aromatic dicarboxylic acids having anionised sulphonate group, for example those of the formula:

wherein M is a cation (preferably sodium, lithium or potassium); andeach R^(c) independently is H, a cation or C₁₋₄-alkyl (preferably methylor ethyl). Preferred compounds of the above formula are of formula:

wherein M and R^(c) are as defined above. Particularly preferred is themono sodium salt (one R^(c) is H, the other is Na), this material beingknown as sodio-5-sulphoisophthalic acid (SSIPA).

Other useful compounds which have two or more groups which readilyundergo an ester condensation reaction and have one or more sulphonategroups are dihydroxy monomers having at least one sulphonate group,especially those of the formula:

wherein M is as hereinbefore defined above and each R^(d) independentlyis alkylene, preferably C₂₋₄-alkylene. Preferred compounds of the aboveformula are:

wherein M is as hereinbefore defined.

Polyesters bearing ionised carboxy groups can be prepared by variousmeans. For example, if the hydroxyl component of the reactants isstoichiometrically in excess of the acid component, ahydroxyl-terminated polyester can be formed, which may be subsequentlyconverted to a carboxy terminated polyester by wholly or partiallyreacting the hydroxyl groups with an appropriate reagent (e.g an acidanhydride or a dicarboxylic acid). Alternatively, terminal carboxyfunctionality may be directly introduced by employing an appropriatestoichiometric excess of the acid component reactants. In anotheralternative, chain-pendant carboxy groups may be introduced by usingreagents such as dimethylol propionic acid (DMPA) since if appropriatereaction condition are employed (e.g. polymerisation temperature below150° C.) the hindered carboxy group thereof does not take part to anysignificant extent in the ester-forming reactions during the polyestersynthesis and the DMPA effectively behaves as a simple diol.Chain-pendant and/or terminal carboxy groups could also be introduced byemploying a tri- or higher functionality carboxylic acid or anhydride inthe polyester synthesis, for example, trimellitic acid or anhydride.Combinations of the above procedures could also be used. It is thus seenthat terminal or side-chain carboxy groups or both can be introduced asdesired. These can be fully or partially neutralised with an appropriatebase to yield ionised carboxy groups. The counter ions used may be asfor the ionised sulphonate groups described above (apart from H+sincethe carboxylic acid groups themselves are normally insufficientlyionised to provide a significant amount of ionised carboxygroups—although F substituents would increase acid strength), withalkali metal ions such as Na⁺, Li⁺ and K⁺ again being particularlypreferred, and ammonium and organic amine derived cations less preferredbecause some have an undesirable odour.

The water-dissipatable polyester may optionally have hydrophilicnon-ionic segments, for example within the polyester backbone (i.e.in-chain incorporation) or as chain-pendant or terminal groups. Suchgroups may act to contribute to the dispersion stability or evenwater-solubility of the polyester. For example, polyethylene oxidechains may be introduced into the polyester during its synthesis byusing as part of the hydroxyl component, ethylene oxide-containing mono,di or higher functional hydroxy compounds, especially polyethleneglycols and alkyl ethers of polyethylene glycols, examples of whichinclude:

wherein R^(e) is C₁₋₂₀-alkyl, preferably C₁₋₄-alkyl, more preferablymethyl; n is 1 to 500; and p is 1 to 100.

A small segment of a polyethylene oxide chain could be replaced by apropylene oxide or butylene oxide chain in such non-ionic groups, butshould still contain ethylene oxide as a major part of the chain.

The amount of ionised sulphonate and/or carboxy groups present in thepolyester should be sufficient to provide or contribute towater-dissipatability of the polyester, although it should not be sohigh as to render the resulting polyester unacceptably water-sensitive.This amount will depend, inter alia, on factors such as thehydrophilicity/hydrophobicity of units provided by other monomers in thepolyester synthesis or any surfactants (if used), and also the relativeproportions of ionised sulphonate/carboxy groups. With regard to thelast mentioned point, ionised sulphonate groups are more effective atproviding or contributing to water-dissipatability than ionised carboxygroups and so can be used at considerably lower levels in comparison toionised carboxy groups.

If the polyester is wholly or predominantly sulphonate stabilised (bywhich is meant the water dissipatability-providing groups are providedwholly or predominately by ionised sulphonate groups). The ionisedsulphonate group content is preferably within the range from 7.5 to 100milliequivalents (more preferably 10 to 75 milliequivalents andparticularly 11 to 56 milliequivalents) per 100 g of polyester. Whenusing SSIPA as the monomer for providing the ionised sulphonate groups,the amount of this monomer used in the polyester synthesis, based on theweight of all the monomers used in the polyester synthesis, will usuallybe within the range from 2 to 20% by weight (more usually 3 to 15% byweight). The carboxylic acid value (AV) of the polyester which ispredominantly sulphonate stabilised, i.e. an AV based on the carboxylicacid groups only (i.e. excluding sulphonate groups) will generally bewithin the range of from 0 to 100 mgKOH/g, more preferably 0 to 50mgKOH/g, especially 0 to 25 mgKOH/g, more especially 0 to 10 mgKOH/g.

If the polyester is predominantly stabilised by ionised carboxy groups,the carboxylic acid value AV of the polyester is preferably within therange of from 20 to 140 mgKOH/g (more preferably 30 to 100 mgKOH/g).

Usually, the polyester is either predominantly sulphonate-stabilised orpredominantly carboxylate stabilised (preferably the former).

If the polyester contains polyethylene oxide chains, the polyethyleneoxide chain content should preferably not exceed 25% by weight (and morepreferably should not exceed 15% by weight), based on the total weightof the polyester, in order to avoid unacceptable water-sensitivity.Therefore the amount is preferably 0 to 25% by weight (more preferably 0to 15% by weight) based on the total weight of polyester.

The water-dissipatable polyester preferably has a number averagemolecular weight Mn of up to 30,000. The Mn is preferably in the rangefrom 500 to 30,000, more preferably 1000 to 25,000, especially 2000 to20,000. These Mn lead to particularly good storage stability for theresultant inks. The measurement of Mn is well known to those skilled inthe art, and may for example be effected using gel permeationchromatography in conjunction with a standard polymer such aspolystyrene or polymethylmethacrylate of known molecular weight.

The water-dissipatable polyester preferably has a hydroxyl number offrom 0 to 225 mg KOH/g, more preferably 0 to 125 mg KOH/g, especiallyfrom 0 to 50 mgKOH/g.

The ink preferably has a pH of 5 to 9, more preferably 5.5 to 8,especially 6 to 7.5. These preferences are based on increased inkstability.

The Tg of the water-dissipatable polyester (i.e. the temperature atwhich the polymer changes from a glassy, brittle state to a plastic,rubbery state) is preferably in the range −38° C. to 105° C., morepreferably −20 to 70° C., especially −10°to 60° C.

The esterification polymerisation processes for making the polyestersfor use in invention composition are known and need not be describedhere in more detail. Suffice to say that they are normally carried outin the melt using catalysts, for example a tin-based catalyst, and withthe provision for removing any water or alcohol formed from thecondensation reaction.

The water-dissipatable polyester may be dissipated in water by addingthe solidified melt directly into water. The solidified melt ispreferably in a form such as flake (which can often be obtained directlyfrom the melt) or comminuted solid (obtained for example by grinding).Alternatively, water can be added directly to the hot polyester meltuntil the desired solids content/viscosity is reached. Still further,the polyester may be dissipated in water by adding an aqueouspre-dissipation (or organic solvent solution) of the polyester to thewater phase.

The water-dissipatable polyesters normally do not need an externalsurfactant when being dissipated into water, although such surfactantsmay be used to assist the dissipation if desired and in some cases canbe useful in this respect because additional surfactants reduce therequired amount of dissipating groups (i.e. suiphonate, and (monoalkoxy)polyalkylene chains if used).

Water-dissipatable polyesters can also be purchased from Eastman KodakCompany. Examples include Eastman AQ29D and AQ55W.

The water-dissipatable polymer may also be formed by performing freeradical polymerisation of olefinically unsaturated monomers in thepresence of a polyester. This gives what could be called apolyester-acrylic hybrid. Olefinically unsaturated monomers which can beused include olefinically unsaturated carboxy functional monomers, e.g.acrylic acid, methacrylic acid, fumaric acid, itaconic acid andβ-carboxyethyl acrylate; olefinically unsaturated monomers which arefree from carboxy and hydroxy groups, e.g. 1,3-butadiene, isoprene,styrene, vinylidene halides, vinylidene esters and esters of acrylicacid and methacrylic acid, e.g. methyl (meth) acrylate, ethyl(meth)acrylate n-butyl (meth)acrylate and 2-ethyl hexyl (meth)acrylate;and olefinically unsaturated monomers having a hydroxy group e.g.N-methylol (meth)acrylamide and hydroxy C₂₋₈-alkyl esters of(meth)acrylic acid. If the polyester has been prepared using a componentwhich has unsaturation therein, e.g. fumaric acid, maleic acid ormuconic acid or allyl-containing dihydroxy or dicarboxy compounds, theproduct from the polyesterification reaction will have unsaturationincorporated into its structure which can take part in the free radicalpolymerisation to give a graft copolymer. The free radicalpolymerisation processes use a free-radical generating initiator systemsuch as (for example) the redox radical initiator system tertiarybutylhydroxide/isoascorbic acid and will take place in the aqueousphase, rather than in the melt. However, excessive amounts of acrylicpolymer (whether formed in the presence of polyester which hasunsaturation or is free from unsaturation) often leads to adeterioration in ink properties and it is preferred that no acrylicpolymer is present or, if its is present, the amount is less than 40%,preferably less than 30%, more preferably less than 10% by weightrelative to the weight of polyester.

The dyed water-dissipatable polymer may be prepared by heating awater-dissipatable polymer and a dye carrying a group of Formula (1) atan elevated temperature, for example at a temperature in the range 35 to150° C. preferably from 40 to 90° C. Simply mixing the dye and polymerin water at room temperature leads to a slight up-take of colour butheating is usually necessary for a full dyeing.

Preferably inks according to the invention are prepared by mixingtogether (i) a solution of a dye carrying a group of Formula (1) in awater-immiscible solvent and (ii) a mixture of a water-dissipatablepolymer, water-miscible solvent and optionally water. Equally the inksmay be prepared by mixing together (i) a solution of a dye carrying agroup of Formula (1) in a mixture of a water-miscible solvent and awater-immiscible solvent and (ii) a water-dissipatable polymer andoptionally water. In either case, if there is no water in component (ii)the water may be added to the mixture of (i) a (ii) subsequently to givean ink according to the invention. However it is preferred for component(ii) to contain water. These processes lead to particularly good up-takeof dye by the polymer to give intensely coloured inks.

The dye is preferably a water-insoluble dye carrying a group of Formula(1) which is soluble in the water-dissipatable polymer. Therefore thedye is preferably free from carboxy and sulpho groups, for example it ispreferably a disperse or solvent-soluble dye carrying a group or Formula(1). Disperse and solvent soluble dyes are distinct from pigments inthat pigments are insoluble in organic solvents and polyesters whereasdisperse and solvent soluble dyes are soluble in organic solvents andpolyesters. Useful classes of disperse and solvent soluble dyes includewater-insoluble anthraquinones, phthalocyanines, pyrrolines,triphenodioxazines, methines, benzodifuranones, coumarins, indoanilines,benzenoids and azoics, each of which carries a group of Formula (1).Examples of preferred azoics are monoazo, disazo and trisazo disperseand solvent soluble dyes; preferred azoics contain heterocyclic groups.The Colour Index International lists suitable disperse and solventsoluble dyes which can be modified to include a group of Formula (1).

Further examples of disperse dyes are given in the Colour Index; 3rdEdition, Volume 2, pages 2483 to 2741 and further examples of solventsoluble dyes are given in Volume 3, pages 3566 to 3647. Each of thesedyes may be modified to incorporate a group of Formula (1).

The amount of dye and water-dissipatable polymer contained in the inkwill vary according to the depth of shade required. Typically, however,the ink will comprise

(a) from 0.5 to 10 parts, more preferably 1 to 5 parts of a dye carryinga group of Formula (1);

(b) from 2 to 25 parts, more preferably 5 to 15 parts of awater-dissipatable polymer;

(c) from 40 to 90 parts, more preferably from 50 to 80 parts of water;and

(d) from 0 to 60 parts, more preferably 0 to 40 parts of organicsolvent; wherein all parts are by weight and the total number of partsof (a)+(b)+(c)+(d) add up to 100.

The number of parts of the water-dissipatable polymer is calculated on a100% solids basis. For example 50 g of a 20% solids polymer is taken as10 g of polymer.

The ink may also contain an organic solvent (as mentioned in (d) above)and this may be a mixture of organic solvents. In a preferred embodimentthe ink contains an organic solvent consisting of a water-miscibleorganic solvent and a water-immiscible organic solvent.

Suitable water-immiscible organic solvents include aromatichydrocarbons, e.g. toluene, xylene, naphthalene, tetrahydronaphthaleneand methyl naphthalene; chlorinated aromatic hydrocarbons, e.g.chlorobenzene, fluorobenzene, chloronaphthalene and bromonaphthalene;esters, e.g. butyl acetate, ethyl acetate, methyl benzoate, ethylbenzoate, benzyl benzoate, butyl benzoate, phenylethyl acetate, butyllactate, benzyl lactate, diethyleneglycol dipropionate, dimethylphthalate, diethyl phthalate, dibutyl phthalate, di (2-ethylhexyl)phthalate; alcohols having six or more carbon atoms, e.g. hexanol,octanol, benzyl alcohol, phenyl ethanol, phenoxy ethanol, phenoxypropanol and phenoxy butanol; ethers having at least 5 carbon atoms,preferably C₅₋₁₄ ethers, e.g. anisole and phenetole; nitrocellulose,cellulose ether, cellulose acetate; low odour petroleum distillates;turpentine; white spirits; naphtha; isopropylbiphenyl; terpene;vegetable oil; mineral oil; essential oil; and natural oil; and mixturesof any two or more thereof. Benzyl alcohol is especially preferred.

Suitable water-miscible organic solvents include C₁₋₅-alkanols, e.g.methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol,tert-butanol and isobutanol; amides, e.g. dimethylformamide anddimethylacetamide; ketones and ketone alcohols, e.g. acetone anddiacetone alcohol; C₂₋₄ether, e.g. tetrahydrofuran and dioxane; alkyleneglycols or thioglycols containing a C₂-C₆ alkylene group, e.g. ethyleneglycol, propylene glycol, butylene glycol, pentylene glycol and hexyleneglycol; poly(alkylene-glycol)s and thioglycol)s, e.g. diethylene glycol,thiodiglycol, polyethylene glycol and polypropylene glycol; polyols,e.g. glycerol and 1,2,6-hexanetriol; and lower alkyl glycol andpolyglycol ethers, e.g. 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol,2-(2-ethoxyethoxy) ethanol, 2-(2-butoxyethoxy)ethanol,3-butoxypropan-1-ol, 2-[2-(2-methoxyethoxy)-ethoxy]ethanol,2-[2-(2-ethoxyethoxy)ethoxy]-ethanol; cyclic esters and cyclic amides,e.g. optionally substituted pyrollidones; sulpholane; and mixturescontaining two or more of the aforementioned water-miscible organicsolvents. Preferred water-miscible organic solvents are C₁₋₆-alkyl monoethers of C₂₋₆-alkylene glycols and C₁₋₆-alkyl mono ethers ofpoly(C₂₋₆-alkylene glycols).

Component (d) of the above mentioned inks preferably comprises;

(i) 5 to 50% of a water-immiscible alcohol having at least six carbonatoms, (especially benzyl alcohol); and

(ii) 50 to 95% of a water-miscible solvent comprising

(a) a cyclic ester or cyclic amide (especially an optionally substitutedpyrrolidone);

(b) a water-miscible C₁₋₆-alkyl mono ether of a C₂₋₆-alkylene glycol orC₁₋₆-alkyl mono ether of poly(C₂₋₆-alkylene glycol); or

(c) a mixture of (a) and (b). wherein all % are by weight and add up to100%.

The water-immiscible solvent preferably has a solubility in water at 20°C. of up to 50g/l. The water-miscible solvent preferably has asolubility in water at 20° C. of more than 50g/l.

The preferred optionally substituted pyrrolidones, are 2-pyrrolidone,dimethyl pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone andN-(2-hydroxyethyl)-2-pyrrolidone and mixtures thereof.

The ratio of water-miscible organic solvent to water-immiscible organicsolvent is preferably 19:1 to 1:1, more preferably 8:1 to 1:1,especially 5:1 to 1:1.

Use of dyes carrying a group of Formula (1) has advantages over the useof pigments in that less dye is usually required than would be the casefor a pigment, expensive milling is avoided, the inks are less likely toform a precipitate on standing, a far greater variety of shades areavailable and the resultant prints have good transparency. The latterquality is particularly important for the production of colouredsubstrates which require transparency, for example over-head projectorslides and colour filters used in LCD television screens. The inks ofthe present invention also benefit from good light- and water-fastness.

A valuable feature of the invention is the low tendency for blocking thenozzles of thermal ink jet printers. Many other water dispersiblepolymer inks work poorly or even not at all in thermal printers. Inks ofthe invention form discrete droplets on the substrate with littletendency for diffusing. Consequently sharp images can be obtained,resulting in excellent print quality and little if any bleed betweencolours printed side-by side.

A further feature of the invention provides a composition comprising awater-dissipatable polymer and a dye which carries a group of Formula(1) as hereinbefore defined. In these compositions the preferredwater-dissipatable polymers and dyes are as hereinbefore described. Suchcompositions may be dissipated in water and optionally mixed withfurther ingredients to give in ink, for example with one or more organicsolvents.

The composition preferably comprises (a) 0.125 to 40 parts of dye whichcarries a group of Formula (1) as hereinbefore defined; and (b) 99.875to 60 parts of a water-dissipatable polymer, wherein the total number ofparts of (a) and (b) adds up to 100.

According to a further feature the present invention provides a processfor printing an image on a substrate comprising applying thereto an inkcomprising water, a water-dissipatable polymer and a dye carrying agroup of Formula (1) as hereinbefore defined, by means of an ink jetprinter.

The ink jet printer emits droplets of the ink onto a substrate from anozzle without bringing the nozzle into contact with the substrate.Preferably the ink jet printer is a thermal or piezoelectric ink jetprinter.

The substrate is preferably a paper, an overhead projector slide or atextile material. Preferred textile materials are cotton, polyester andblends thereof.

When the substrate is a textile material the process for printing animage thereon according to the invention preferably further comprisesthe step of heating the resultant printed textile, preferably to atemperature of 50° C. to 250° C.

The inks of the present invention may also be used for the preparationof colour filters, for example those used in flat bed displays.

The invention is further illustrated by the following examples in whichall parts and percentages are by weight unless specified otherwise. Inthese Examples the following abbreviations are used:

Paper XA is Xerox 4024 from Rank Xerox.

Paper GB is Gilbert Bond paper from the Mead Corporation.

Paper WC is Wiggins Conqueror High White Wove 100 g/m² from Arjo WigginsLtd.

means not measured.

Water-Dissipatable Polymer (“Resin 1”)

To a glass reactor fitted with distillation column and condenser werecharged ingredients A, B, D, F, G and 50% of C and 50% of H. Thecontents were heated with stirring to a reaction temperature of 210° C.until the mixture was clear and the acid value was <10 mgKOH/g. At thispoint E and the remainder of C and H were charged and the temperatureraised to 230° C. The reaction was continued under reduced pressureuntil an acid value of 5.3 mgKOH/g was obtained. The resin was furthercharacterised by a hydroxyl value=27.6 mgKOHg, ICI Cone and Plateviscosity @ 125° C.=80 poises and a Tg (onset)=25.4° C. and a numberaverage molecular weight by end group analysis of approximately 2000.The resin was readily dispersed in warm distilled water to give a clearsolution having a solids content of 20% w/w (hereinafter “Resin 1”).

Monomer Abbreviation Weight (g) neopentyl glycol A 206.25 diethyleneglycol B 82.5 isophthalic acid C 300 sodio-5-sulpho-isophthalic acid D75 adipic acid E 37.5 methoxy PEG 750 F 75 sodium acetate G 1.5 Fascat4101 H 0.75

Water-dissipatable Polymer (“Resin 2”)

To a glass reactor fitted with distillation column and condenser werecharged ingredients A, B, C, E, G, H and 50% of D and 50% of I. Thecontents were heated with stirring to a reaction temperature of 210° C.until the mixture was clear and the acid value was 1.25 mgKOH/g. At thispoint F and the remainder of D and I were charged and the temperatureraised to 230° C. The reaction was continued under reduced pressureuntil an acid value of 2.8 mgKOH/g was obtained. The resin was furthercharacterised by a hydroxyl value=19.7 mgKOH/g, ICI Cone and Plateviscosity @ 125° C.=90 poises and a Tg (onset)=4° C. The resin wasreadily dispersed in warm distilled water to give a clear solutionhaving a solids content of 20% w/w. (hereinafter “Resin 2”).

Monomer Abbreviation Weight (g) neopentyl glycol A 653.47 diethyleneglycol B 479.21 1,6 hexane diol C 396.04 isophthalic acid D 1584.16sodio-5-sulpho-isophthalic acid E 396.04 adipic acid F 198.02 methoxyPEG 750 G 396.04 sodium acetate H 8 Fascat 4101 I 4

Water-Dissipatable Polymer (“Resin 3”)

To a glass reactor fitted with distillation column and condenser werecharged ingredients A, B, D, E, F, G and 50% of C and 50% of H. Thecontents were heated with stirring to a reaction temperature of 210° C.until the mixture was clear and the acid value was <10 mgKOH/g. At thispoint the remainder of C and H were charged and the temperature raisedto 230° C. The reaction was continued under reduced pressure until anacid value of 9.4 mgKOH/g was obtained. The resin was furthercharacterised by a 15 hydroxyl value=3.4 mgKOHg, ICI Cone and PlateViscosity @ 125° C.=>500 poises and a Tg (onset)=18° C. The numberaverage molecular weight by end group analysis was 8766. The resin wasreadily dispersed in warm distilled water to give a clear solutionhaving a solids content of 20% w/w (hereinafter “Resin 3”).

Monomer Abbreviation Weight (g) neopentyl glycol A 15 diethylene glycolB 10 isophthalic acid C 45 sodio-5-sulpho-isophthalic acid D 10Hexane-1,6-diol E 10 Methoxy PEG 750 F 10 Sodium acetate G 0.2 Fascat4101 H 0.1

EXAMPLE 1

A dye of the formula shown below was prepared by using stages 1a to 1cdescribed below:

Stage 1a—3-(N-sec-butylamino)acetanilide

3-Aminoacetanilide (186.2 g), 2-bromobutane (198 g), triethylamine (150g) and ethanol (1 litre) were heated under reflux for 64 hrs. Aftercooling to room temperature the reaction mixture was filtered to removetriethylamine hydrochloride and the solvent evaporated under reducedpressure to leave a dark oil which was purified by chromatrography onsilica gel. The product was crystallised by trituration under hexane.

Stage 1b—3-(N-n-butyl-N-sec-butylamino) acetanilide

The product from Stage 1a (20.6 g), 1-bromobutane (63.7 g) and anhydrouspotassium carbonate (13.89) were stirred and heated under reflux for 36hours. The cooled reaction mixture was diluted with methanol (50 ml) andfiltered to remove the inorganic salts. Evaporation of the excessbromobutane and methanol under reduced pressure gave a viscous oil whichwas purified by chromatography on silica gel.

Stage 1c—Dye 1

4-Nitrobenzenediazonium fluoroborate (1.18 g) was dissolved in a mixtureof water (50 ml) and hydrochloric acid (2.5 ml) and added to an ice coldsolution of the product from stage 1b (1.31 g) in dilute hydrochloricacid (50 ml). Sodium acetate was added to raise the pH to 4 to 4.5 andthe resulting dye recovered by filtration, washed with alcohol anddried.

Dye 1 was obtained as an orange solid (1.5 g).

Stage 2—Ink Preparation

An ink was prepared by dissolving Dye 1 in benzyl alcohol and adding thewater-dissipatable polyester (in water and 2-pyrrolidone) to the dyesolution.

The final ink had the formulation:

Component Weight (g) Dye 1 0.25 Resin 1 50 g (20% solids) Benzyl alcohol10 2-pyrrolidone 20 Water 19.75 100

EXAMPLE 2

Stage 1

A dye having the formula shown below was prepared by the methoddescribed in stages 1a to 1d below:

Stage 1a

N-sec-butyl-3-toluidine

3-Toluidine (107.16 g), 2-butanone (72.11 g) and propionic acid (74.08g) were stirred and cooled to 0° C. Sodium borohydride (37.83 g) wasthen added in portions keeping the temperature below 5° C. Afterallowing to warm to room temperature the reaction mixture was carefullypoured onto ice/water. The product was extracted into ethyl acetate,washed with water, 2% hydrochloric acid and finally water again beforedrying over magnesium sulphate. Evaporation of the solvent under reducedpressure gave a brown oil which was purified by chromatography on silicagel.

Stage 1b—N-n-Butyl-N-sec-butyl-3-toluidine

The method of Example 1, stage 1b, was repeated except that in place ofthe product from Example 1, stage 1a, there was used the product fromExample 2, stage 1a.

Stage 1c

N-n-Butyl-N-sec-butyl-3-toluidine (10.95 g) was dissolved in dimethylformamide (150 ml) and cooled to 0-5° C. Phosphorus oxychloride (15.3 g)was then added dropwise keeping the temperature below 5° C. Afterallowing to warm to room temperature the reaction mixture was heated to80° C. for 2½ hours, cooled and powered onto ice. The product wasextracted into toluene, dried over magnesium sulphate and isolated byevaporation of the solvent under reduced pressure and purified bychromatography on silica gel.

Stage 1d—Dye 2

4-(N-n-butyl-N-sec-butylamino)-2-methylbenzaldehyde (29) andethylcyanoacetate (1 ml) were dissolved in ethanol (5 ml). Piperidine (3drops) was added and the mixture stirred at room temperature from 30minutes. Evaporation of the solvent gave an orange oil whichcrystallised on trituration under hexane.

Dye 2 was obtained as a yellow solid (2.6 g).

Stage 2—Ink Preparation

An ink formulation of the composition:

Component Weight (g) Dye 2 1 Resin 2 50 (20% solids) benzyl alcohol 102-pyrrolidone 20 Water 19 100

was prepared by the method described in stage 2 of Example 1.

COMPARATIVE EXAMPLE 1

An ink was prepared as described in Example 1 except that in place ofDye 1 there was used Dye 3 shown below:

COMPARATIVE EXAMPLE 2

An inks was prepared as described in Example 2 except that in place ofDye 2 there was used Dye 4 shown below:

EXAMPLE 3

IJP Using the Ink

The inks descrided in Examples 1 and 2 and in the comparative Exampleswere printed onto three commercially available papers, as described inTable 1 below, using a Hewlett Packard themal ink jet printer. Theprints resulting from inks 1 and 2 had very good Colour strength andbrightness (chroma).

The prints were irradiated with light using an Atlas Ci35 Weatherometerand the colour change (ΔE) was measured after the time indicated inTable 1:

TABLE 1 ΔE on ΔE on ΔE on Ink Time (hours) paper XA paper GB paper WCDye 1 24 12.9 12.75 11.69 48 18.61 18.25 18.47 72 25.03 21.47 24.43 10025.75 26.85 29.79 Dye 3 24 19.45 19.37 17.37 (Comparative) 48 26.5124.91 25.53 72 31.41 29.27 32.15 100 36.77 31.69 35.71 Dye 2 24 14.11 —20.11 48 31.55 — 40.11 72 48.79 — 59.99 Dye 4 24 19.41 — 29.13(Comparative) 48 44.85 — 59.33 72 59.53 — 70.43 The lower ΔE for Dye 1and Dye 2 versus Dye 3 and Dye 4 show lower fading (i.e. higher lightfastness).

The lower ΔE for Dye 1 and Dye 2 versus Dye 3 and Dye 4 show lowerfading (i.e. hihger light fastnees).

EXAMPLE 6

Stage 1

The method of Example 2, stage 1 was repeated except that in place ofethlcyanoacetate there was used malononitrile. The resultant dye had thestructure:

Stage 2—Comparative

Similarly a dye was prepared having the following structure:

Stage 3—Inks

Inks containing Dye 5 or Dye 6 were prepared having the followingformulation:

Dye 1 g Benzyl Alcohol 10 g 2-Pyrrolidone 20 g Resin 2 50 g (20% solids)Morpholine 1 g Water 18 g

Stage 4—Ink Jet Printing

Inks containing Dye 5 and Dye 6 respectively were printed onto Xeroxacid paper using an ink jet printer. The prints were irradiated withlight using an Atlas Ci35 Weatherometer and the colour change (ΔE) CIELab recorded in the table below.

Dye in Ink Time (Hours) ΔE Dye 5 24 3.11 Dye 5 48 15.61 Dye 5 72 22.25Dye 6 (Comparative) 24 4.91 Dye 6 (Comparative) 48 19.11 Dye 6(Comparative) 72 29.73

The lower figures for Dye 5 show that this dye had better light fastnessthan isomeric Dye 6.

EXAMPLE 7

Preparation of:

5-Amino-4-cyano-3-methylisothiazole

The title compound was prepared according to the method described inJ.Heterocyclic chem. 1975 12 883.

Stage 1b

3-(N-iso-propylamino)acetanilide

The method of Example 2 stage 1a was repeated except that in place of3-toluidine there was used 3-aminoacetanilide and 2-butanone wasreplaced by 2-propanone.

Stage 1c

3-(N-n-butyl-N-iso-propylamino)acetanilide

The method of Example 1, stage 1b was repeated but replacing the productfrom Example 1 stage la by the product from Example 7 stage 1b.

Stage 1d

A mixture of acetic acid (30 ml), propionic acid (5 ml), sulphuric acid(2 ml) and nitrosyl sulphuric acid (7ml, 40% w/w soln) was stirred andcooled to −5 to 0° C. and 5-amino-4-cyano-3-methylisothiazole (2.7 g)was added portionwise. After stirring at −5 to ° C. for 3 hours excessnitrosyl sulphuric acid was destroyed by the addition of sulphamic acid.The resulting diazonium salt solution was then added slowly at 0-5° C.to a solution of the product from Example 7, stage 1c (4.97 g), inmethanol (100 ml) to which sodium acetate (5.5 g) had been added. Afterstirring for 1 hour, water (250 ml) was added and the oily productextracted into dichloromethane and dried over magnesium sulphate. Thecrude product obtained on evaporation of the solvent under reducedpressure was purified by chromatrogaphy on silica gel to give Dye 7.

Stage 2—Comparative

The method of Stage 1d was repeated except that in place of the productfrom Example 7, Stage 1c, there was used3-(N,N-di-n-butylamino)acetanilide to give Dye 8.

Stage 3—Inks

Inks containing Dye 7 or Dye 8 were prepared having the followingformulation:

Stage 4—Ink Jet Printing

Inks from Stage 3 containing Dye 7 and Dye 8 respectively were printedonto Xerox acid paper using an ink jet printer. The prints wereirradiated using an Atlas Ci35 weatherometer and the colour change (ΔE)recorded in the Table below:

Dye in Ink Time (hours) ΔE 7 24 10.55 7 48 13.59 7 72 16.23 7 100 20.738 (Comparative) 24 12.89 8 (Comparative) 48 16.63 8 (Comparative) 7220.61 8 (Comparative) 100 24.73

EXAMPLE 8

Stage 1

Preparation of:

Stage 1

The method of Example 7 Stage 1d was repeated except that in place of5-amino-4-cyano-3-methylisothiazole there was used2-bromo-4,6-dinitroaniline (5.24 g) and in place of the product fromExample 7 Stage 1c was used Example 1 Stage 1b (5.25 g).

Stage 2—Comparative

Preparation of:

Stage 2a—3-(N,N-bis-(2-methylprop-1-yl)amino)acetanilide

3-Aminoacetanilide (74.4 g), 1-bromo-2-methylpropane (164 g), water (600ml) and calcium carbonate (118 g) were stirred and heated to reflux for20 hours. After cooling to room temperature dichloromethane (250 ml) wasadded and the mixture filtered, washing the filter cake withdichloromethane (2×100 ml). The organic phase was separated, dried overmagnesium sulphate and the solvent together with excess1-bromo-2-methylpropane was evaporated under reduced pressure to give adark brown viscous oil. This product was used without furtherpurification.

Stage 2b

The method of Example 7 Stage 1d was repeated except that in place of5-amino-4-cyano-3-methylisothiazole there was used2-bromo-4,6-dinitroaniline (5.24 g) and in place of the product fromExample 7 Stage 1c there was used Example 8 Stage 2a.

Stage 3—Inks

Inks containing Dye 9 or Dye 10 were prepared having the followingformulations:

Dye 1 g Benzyl Alcohol 10 g 2-Pyrrolidone 20 g Resin 1 50 g (20% solids)Water 19 g

Stage 4—Ink Jet Printing

Inks from Stage 3 containing Dye 9 and Dye 10 respectively were printedonto Xerox acid paper using an ink jet printer. The resultant change incolour (ΔE) after 100 hours irradiation were: Dye 9 ΔE=29.83; Dye 10(Comparative) ΔE=37.27.

EXAMPLE 9

Stage 1

Preparation of

Stage 1a

2-Amino-4,6-dichloro-5-methylphenol

The title compound may be prepared as disclosed in Chemical Abstracts78:97311

Stage 1b

2-Acetylamino-4,6-dichloro-5-methylphenol

The product from Example 9, Stage 1a (4.8 g), was stirred in acetic acid(20 ml) and acetic anhydride (5 ml) was added in one portion. Stirringwas continued for 1hour after the initially exothermic reaction hadsubsided. The product was isolated by filtration and recrystallised fromaqueous ethanol.

Stage 1c

3-(N-sec-butyl-N-ethyl)toluidine

The method of Example 1, Stage 1b, was repeated replacing 1-bromobutaneby iodoethane.

Stage 1d

N-sec-butyl-N-ethyl-4-nitroso-3-toluidine

The product from Stage 1c (9.57 g) was dissolved in hydrochloric acid(20 ml) and the solution cooled to 0-5° C. A solution of sodium nitrite(3.45 g) in water (15 ml) was added dropwise at 0-5° C. and the mixturefurther stirred for 1 hour at room temperature before drowning intowater (100 ml). The pH was adjusted to 9 with dilute sodium hydroxidesolution and the product extracted into dichloromethane (2×100 ml). Theorganic phase was separated, dried over magnesium sulphate, filtered andthe solvent removed under reduced pressure to give a greenish yellow oilwhich was used without further purification.

Stage 1e

4-Amino-N-sec-butyl-N-ethyl-3-toluidine

A suspension of iron powder (8.34 g) in methanol (60 ml) andhydrochloric acid (20 ml) was stirred at reflux for 15 mins. A solutionof the product from Stage 1d (11 g) in methanol (60 ml) was addeddropwise over 15 mins and refluxing continued for 3 hours. Sodiumcarbonate was added until no soluble iron remained and the solution wasalkaline to Brilliant Yellow paper. The hot reaction mixture wasfiltered and the solvent removed under reduced pressure to give theproduct as a brown oil.

Stage 1f

Preparation of Dye 11

The product from Stage 1b (2.34 g) was stirred in acetone (50 ml) and asolution of sodium carbonate (3.88 g) in water (20 ml) added followed bythe product from Stage le (2.06 g). A solution of ammonium persulphate(4.56 g) in water (30 ml) was then added and stirring continued for 2hours. The product was isolated by filtration, washed with water anddried before purification by column chromatography on silica gel.

Stage 2—Comparative

Preparation of:

Stage 2a

The method of Example 9, Stage 1d, was repeated replacing the productfrom Example 9 Stage 1c by N,N-diethyl-3-toluidine.

Stage 2b

The method of Example 9, Stage 1e, was repeated replacing the productfrom Example 9 Stage 1d by the product from Example 9 Stage 2a.

Stage 2c

The method of Example 9, Stage 1f, was repeated replacing the productfrom Example 9, Stage 1e, by the product from Example 9 Stage 2b.

Stage 3—Inks

Inks containing Dye 11 or Dye 12 were prepared having the followingformulation

Dye 1 g Benzyl Alcohol 10 g 2-Pyrrolidone 20 g Resin 3 45 g (20% solids)Water 24 g

Stage 4—Ink Jet Printing

Inks from stage 3 containing Dye 11 and Dye 12 respectively were printedonto Xerox Acid Paper and Wiggins Conqueror paper. The prints wereirradiated and the colour change (ΔE) were as follow:

Dye in ink Paper Δ (100 hours) 11 XA 21.41 12 (Comparative) XA 26.09 11WC 17.27 12 (Comparative) WC 32.01

What is claimed is:
 1. An ink comprising water, a water-dissipatablepolymer and a dye, wherein the dye carries a group of the Formula (1):

wherein: R¹ is optionally substituted branched chain alkyl; and R² is H,optionally substituted alkyl or optionally substituted aryl.
 2. An inkaccording to claim 1 wherein R¹ is α-branched optionally substitutedalkyl.
 3. An ink according to claim 1 wherein R¹ is a group of theformula —CHR³R⁴ wherein R³ and R⁴ are each independently optionallysubstituted alkyl or R³ and R⁴ together with the CH group to which theyare attached form an optionally substituted 5- or 6-membered ring.
 4. Anink according to claim 1, 2 or 3 wherein R¹ has from 3 to 20 carbonatoms.
 5. An ink according to claim 1, 2 or 3 wherein R¹ is prop-2-yl,but-2-yl, pent-2-yl, pent-3-yl, hex-2-yl, hex-3-yl, hept-2-yl,cyclopentyl or cyclohexyl.
 6. An ink according to claim 1, 2 or 3wherein the dye is of the formula:

wherein: A is the residue of a diazotisable aromatic or heterocyclicamine; B is an optionally substituted 1,4-phenylene group; and R¹ and R²are as hereinbefore defined.
 7. An ink according to claim 1, 2 or 3wherein the dye is of the formula:

wherein: X¹ is N or C; a is 0 when X¹ is N; a is 1 when X¹ is C; R¹⁹ is—H, —CN or —COOalkyl; B is an optionally substituted 1,4-phenylenegroup; R¹ and R² are as hereinbefore defined; and Y¹ is a homocyclicring, a heterocyclic ring, a carbon atom carrying an electronwithdrawing group or Y¹ together with X¹ and (R¹⁹)a forms a homocyclicor heterocyclic ring.
 8. An ink according to claim 1, 2 or 3 wherein thewater-dissipatable polymer is a water-dissipatable polyester.
 9. An inkaccording to claim 8 wherein the water-dissipatable polyester bearsionised sulphonate and/or carboxy groups.
 10. An ink according to claim8 wherein the water-dissipatable polyester has an Mn of below 30,000.11. An ink according to claim 1, 2 or 3 comprising: (a) from 0.5 to 10parts of the dye carrying a group of Formula (1); (b) from 2 to 25 partsof the water-dissipatable polymer; (c) from 40 to 90 parts of water; and(d) from 0 to 60 parts of an organic solvent; wherein all parts are byweight and the total number of parts of (a)+(b)+(c)+(d) add up to 100.12. A composition comprising a water-dissipatable polymer and a dyewhich carries a group of Formula (1), as defined in claim
 1. 13. Acomposition according to claim 12 wherein the water-dissipatable polymeris a water-dissipatable polyester.
 14. An ink according to claim 1, 2 or3 which contains a water-miscible organic solvent and a water-immiscibleorganic solvent.
 15. A process for printing an image on a substratecomprising applying thereto an ink according to claim 1, 2 or 3 by meansof an ink jet printer.
 16. An ink according to claim 6, comprising: (a)from 0.5 to 10 parts of the dye carrying group of Formula (1); (b) from2 to 25 parts of the water-dissipatable polymer; (c) from 40 to 90 partswater; and (d) from 0 to 60 parts of an organic solvent; wherein allpars are by weight and the total number of parts (a)+(b)+(c)+(d) add upto
 100. 17. An ink according to claim 7, comprising: (a) from 0.5 to 10parts of the dye carrying group of Formula (1); (b) from 2 to 25 partsof the water-dissipatable polymer; (c) from 40 to 90 parts water; and(d) from 0 to 60 parts of an organic solvent; wherein all pars are byweight and the total number of parts (a)+(b)+(c)+(d) add up to
 100. 18.A process for printing an image on a substrate comprising applyingthereto an ink according to claim 6 by means of an ink printer.
 19. Aprocess for printing an image on a substrate comprising applying theretoan ink according to claim 7 by means of an ink printer.